He said: "We carry some lithium ion batteries but they are approved and not declared as dangerous goods.

"Airlines do this all the time; these goods have been flown many times."

One of the theories behind the plane's disappearance has focused on a fire breaking out and causing the pilots to become incapacitated.

But David Learmount, operations and safety editor of Flightglobal, said the pilots would have alerted air traffic control if a fire broke out onboard.

He told Sky News Online: "The problem if you have a lot of them (batteries) and they start reacting with each other is that they cause an enormous amount of heat and that causes fire.

Dreamliner aircraft were grounded in 2013 after fires caused by batteries

"The pilots would be immediately aware because of detectors and fires in the hold can be very dangerous because you can't get into it from the aircraft.

"They would be turning for the nearest airport as fast as possible and telling air traffic control - fire on any aircraft is absolutely terrifying for everyone.

Video:The Difficult Search For Debris

"This aircraft has not come down because of fire. The idea that a pilot would keep a fire quiet is absolutely unthinkable."

Mr Learmount said the theory that the aircraft was deliberately turned off course by someone who knew what they were doing was the most plausible explanation for its disappearance.

Malaysian authorities have said the plane turned west and travelled back over the Malay Peninsula and out into the Indian Ocean after it vanished from radar during its flight from Kuala Lumpur to Beijing on March 8.

Video:FBI Agent: MH370 A 'Criminal' Act

The last contact with the Boeing 777 was heard from the cockpit, when a person thought to be the co-pilot said "all right, good night" to Malaysian air traffic control at 1.19am.

An international search team scoured areas of the southern Indian Ocean on Friday for sign of objects spotted by a satellite which could potentially be debris.